Simplification and Intensification of a C5 Separation Process

The C5 fraction, which accounts for 15–25% in naphtha, consists of molecules such as isoprene (IP), pentadiene (PD), cyclopentene (CP), and cyclopentadiene (CPD). The C5 fraction can be used to manufacture petroleum resin and other high-value-added products. Yet it is often burned as fuel and not fully utilized because separation of these products with close boiling points is difficult. One common process is to react CPD with itself to form high boiling dicyclopentadiene (DCPD) that can then be separated from other C5 molecules. In addition, extractive distillation is also used to recover alkynes from light ends. Such a process involves the use of multiple separation columns and reaction zones. Furthermore, the reactor is highly coupled with one of the separation columns by two recycle streams, which may lead to a snowball effect and difficulty in controlling the process. Hence, many opportunities for process integration and intensification are available. We describe how the entire process with reaction and separation can be substantially simplified by reducing the number of reaction zones from two to one and the number of columns from eight to six. Such a simplification increases not only process operability but also product concentration of DCPD, while maintaining a high purity for the IP stream and a specified purity for the PD plus CP stream. Moreover, capital cost can be greatly decreased with the simplified process. This process can be further intensified by using thermal coupling and external heat integration. Large energy savings can be achieved for the intensified process. Simulation results demonstrate that the proposed simplified and intensified process for the separation of a C5 mixture can substantially reduce capital and operating costs as well as improve process operability and increase the main product purity of DCPD.